The present invention generally relates to an electric motor, and more. particularly, to an electric motor having cooling circuits which permit flow of cooling media in the motor housing.
A known type of electrical motor device is disclosed in Japanese Patent Laid-Open Publication No. 11-69672 published on Mar. 9, 1999. The disclosed electric motor includes a frame. The frame is substantially composed of a cylindrical outer frame and a inner frame which supports a stator core and seal mechanism which is arranged at an outer peripheral edge portion. A groove is formed on the whole surface of the inner frame. A cooling path is defined between the inner surface of the outer frame and the outer surface of the inner frame. The leakage of the cooling media is prevented by using a seal mechanism.
In terms of low-cost, light weight and a high heat discharge efficiency, the frame is made by using a diecasting process. According to the Japanese Publication No. 11-69672, a high efficiency heat discharge can be obtained, however, a complicated cooling path structure is required. The complicated cooling path structure causes a relatively high manufacturing cost.
The object of the present invention is to produce a frame for an electric motor which has a high heat discharge efficiency with a low manufacturing cost.
To achieve the object of the present invention, an electric motor having a heat discharge structure comprises a frame having a cylindrical shaped bore which accommodates an electric coil and a stator core, the frame having a diecast block which having a rectangular shaped cross section, the diecast block having a plurality of grooves and paths which allows a flow of cooling media, the diecast block having a plurality of communication paths which are formed along with outer surface of the casting block and communicate between the grooves.
According to the invention, high heat discharge efficiency with low manufacturing cost can be achieved.